Spectral structure of beating tsumamis observed in Japan

We studied the spectral structure of beating tsunamis. Selecting 10 beating tsunamis from tide gauge records of tsunamis in Japan we decomposed them into the spectra. We extracted the spectral components contributing to the beat under the assumption that a beat consists of two sinusoidal waves and compared them with dominant frequencies of background oscillations, which had been observed around the same tide stations as the records were obtained. The two spectral components are found as the highest ones in dominant frequencies. Since one of them was equal to fundamental or higher modes of the background oscillation in the frequency, we concluded that tsunami excited some mode of the background oscillation and it caused a resonance of the bay or port. Large decays of the spectra found in the frequency range above the exciting frequencies result from a defect of the higher frequency components in the incident tsunami

Spectral structure of beating tsunamis observed in Japan

We studied the spectral structure of beating tsunamis. Selecting 10 beating tsunamis from tide gauge records of tsunamis in Japan we decomposed them into the spectra. We extracted the spectral components contributing to the beat under the assumption that a beat consists of two sinusoidal waves and compared them with dominant frequencies of background oscillations, which had been observed around the same tide stations as the records were obtained. The two spectral components are found as the highest ones in dominant frequencies. Since one of them was equal to fundamental or higher modes of the background oscillation in the frequency, we concluded that tsunami excited some mode of the background oscillation and it caused a resonance of the bay or port. Large decays of the spectra found in the frequency range above the exciting frequencies result from a defect of the higher frequency components in the incident tsunami